Claims:

1. An anti-graffiti surface coating consisting essentially of the
combination of:alkali metal silicate;ethylene-glycol colloidal
silica;aminopropyl oxysilane;fluorinated polyurethane; andalkali metal
methyl siliconate;the coating characterized in that it is a
surface-penetrating coating, is chemically resistant, and possesses a
surface tension higher than the surface tension of the surface to which
it is applied, whereby paint applied to said coating is easily removed.

2. The coating of claim 1, wherein:said alkali metal silicate is present
in the combination in the range of approximately 40 to 60 wt %;said
ethylene-glycol colloidal silica is present in the combination in the
range of approximately 5 to 20 wt %;said aminopropyl oxysilane is present
in the combination in the range of approximately 0.5 to 1.5 wt %;said
fluorinated polyurethane is present in the combination in the range of
approximately 10 to 30 wt %; andsaid alkali metal methyl siliconate is
present in the combination in the range of approximately 10 to 30 wt %.

3. The coating of claim 1, further comprising deionized water.

4. The coating of claim 2, further comprising deionized water.

5. The coating of claim 4, wherein said deionized water is present in the
combination in an amount up to approximately 10 wt %.

6. The coating of claim 1, wherein said alkali metal silicate is chosen
from the group of alkali metal silicates consisting of potassium
silicate, lithium silicate and sodium silicate.

7. The coating of claim 2, wherein said alkali metal silicate is chosen
from the group of alkali metal silicates consisting of potassium
silicate, lithium silicate and sodium silicate.

8. The coating of claim 3, wherein said alkali metal silicate is chosen
from the group of alkali metal silicates consisting of potassium
silicate, lithium silicate and sodium silicate.

16. An anti-graffiti surface coating consisting of the combination
of:alkali metal silicate;ethylene-glycol colloidal silica;aminopropyl
oxysilane;fluorinated polyurethane; andalkali metal methyl siliconate;the
coating characterized in that it is a surface-penetrating coating, is
chemically resistant, and possesses a surface tension higher than the
surface tension of the surface to which it is applied, whereby paint
applied to said coating is easily removed.

17. The coating of claim 16, wherein:said alkali metal silicate is present
in the combination in the range of approximately 40 to 60 wt %;said
ethylene-glycol colloidal silica is present in the combination in the
range of approximately 5 to 20 wt %;said aminopropyl oxysilane is present
in the combination in the range of approximately 0.5 to 1.5 wt %;said
fluorinated polyurethane is present in the combination in the range of
approximately 10 to 30 wt %; andsaid alkali metal methyl siliconate is
present in the combination in the range of approximately 10 to 30 wt %.

18. The coating of claim 16, further comprising deionized water.

19. The coating of claim 16, wherein said alkali metal silicate is chosen
from the group of alkali metal silicates consisting of potassium
silicate, lithium silicate and sodium silicate.

[0002]This invention relates generally to the field of surface treatments
and coatings for substrates and surfaces, and more particularly relates
to treatments and coatings that possess anti-graffiti properties.

[0003]A common problem encountered with exterior surfaces that are exposed
in public places, such as building walls, storage tanks, railroad cars,
etc., is that such surfaces are often defaced and vandalized with spray
paint or other marking materials by so-called graffiti artists. This is a
worldwide problem and the total aggregate of the time and expense
involved in the removal or covering over of the graffiti is immense.

[0004]One solution to address the graffiti problem is to provide coatings
for the surfaces that prevent the spray paint or other marking material
from properly adhering to the surfaces at the time it is applied, such
that it becomes impossible for the graffiti artist to create a work of
acceptable quality, thereby discouraging the effort. Another solution is
to provide coatings that, while not affecting the adherence of the spray
paint to any great degree at the time of application, reduce the adhesion
of the cured paint such that it is easily removed from the surface at a
later time, such as by pressure washing or wiping with solvents, for
example. Many common anti-graffiti coatings are polyurethane-based.
Unfortunately, these PU coatings and similar coatings are only surface
coatings and are therefore considered as sacrificial coatings, in the
sense that the anti-graffiti coatings need to be reapplied after only a
few cleanings with solvents or by pressure washing because the cleaning
process removes the outer layer of the anti-graffiti coating along with
the spray paint. In addition, the vandal community has learned to remove
the known anti-graffiti coatings using fire or acids prior to vandalizing
the surfaces.

[0005]It is an object of this invention to provide a novel coating that
possesses anti-graffiti properties, such that graffiti applied to the
coating is easily removed. It is a further object to provide such a
coating that is a penetrating coating, such that it is not merely a
surface coating. It is a further object to provide such a penetrating
coating that is applicable to most surfaces, including metal, organic or
inorganic surfaces. It is a further object to provide such a penetrating
coating that is highly resistant to fire or chemical attack, and which
provides a surface with high surface tension to reduce the adhesion of
the paint. It is a further object to provide such a penetrating coating
that has a long working life and remains effective over many cleanings by
solvents or pressure washing, for example up to 25 to 30 cleanings. This
object and additional objects not expressly stated will become apparent
upon review of the remaining disclosure.

SUMMARY OF THE INVENTION

[0006]The invention is a non-sacrificial, anti-graffiti coating that
penetrates the substrate surface in addition providing a protective outer
layer, the coating providing a surface possessing high surface tension
and high chemical resistance against the solvents within the spray paint
and other marking materials, such that the spray paint and like marking
materials will not adequately adhere to the coating and is easily
removed, such as by wiping within an hour or so of application, or later
by simple hose washing. The anti-graffiti coating of the invention
remains effective for a significantly greater number of cleanings than
known anti-graffiti coatings, is resistant to degradation or removal by
fire or chemical attack, and does not significantly alter the appearance
of the surface to which it is applied, the anti-graffiti coating being
relatively transparent and low gloss.

[0007]In general, the non-sacrificial, penetrating, anti-graffiti coating
consists essentially of the combination of alkali metal silicate, such as
for example potassium, lithium or sodium silicate, ethylene-glycol
colloidal silica, aminopropyl oxysilane, fluorinated polyurethane, and
alkali metal methyl siliconate, such as for example potassium, lithium or
sodium siliconate. Deionized water is optionally added to alter the
viscosity of the coating.

DETAILED DESCRIPTION OF THE INVENTION

[0008]The invention is a non-sacrificial, anti-graffiti coating that
penetrates the substrate surface in addition providing a protective outer
layer, the coating providing a surface possessing high surface tension
and high chemical resistance against the solvents within the spray paint
and other marking materials, such that the spray paint and like marking
materials will not adequately adhere to the coating and is easily
removed, such as by wiping within an hour or so of application, or later
by simple hose washing. The anti-graffiti coating of the invention
remains effective for a significantly greater number of cleanings than
known anti-graffiti coatings, is resistant to degradation or removal by
fire or chemical attack, and does not significantly alter the appearance
of the surface to which it is applied, the anti-graffiti coating being
essentially transparent and possessing a low gloss or flat finish. The
coating may be applied using conventional techniques, such as brushing,
spraying, rolling, immersing, etc.

[0009]In general, the non-sacrificial, penetrating, anti-graffiti coating
consists essentially of the combination of alkali metal silicate, such as
for example potassium, lithium or sodium silicate, ethylene-glycol
colloidal silica, aminopropyl oxysilane, fluorinated polyurethane, and
alkali metal methyl siliconate, such as for example potassium, lithium or
sodium siliconate. Deionized water is optionally added to alter the
viscosity of the coating.

[0010]In a preferred embodiment, the alkali metal silicate is present in
the combination in the range of approximately 40 to 60 wt %, the
ethylene-glycol colloidal silica is present in the combination in the
range of approximately 5 to 20 wt %, the aminopropyl oxysilane is present
in the combination in the range of approximately 0.5 to 1.5 wt %, the
fluorinated polyurethane is present in the combination in the range of
approximately 10 to 30 wt %, and the alkali metal methyl siliconate is
present in the combination in the range of approximately 10 to 30 wt %.
Deionized water is optionally added up to approximately 10 wt % to thin
the composition for ease of application. A biocide additive may also be
added into the coating composition.

[0011]It is contemplated that equivalents and substitutions for elements
set forth above may be obvious to those of ordinary skill in the art, and
therefore the true scope and definition of the invention is to be as set
forth in the following claims.